Apparatus for drawing filaments

ABSTRACT

Apparatus for continuously drawing a filament comprising a filament advancing roll adapted for rotation under the speed controlling influence of a motor and a plurality of other rolls each adapted for rotation under the speed controlling influence of surface contact with the advancing filament before it reaches the advancing roll at least two of such plurality of rolls being coupled for rotation at a predetermined surface speed ratio corresponding to a required draw ratio.

United States Patent 11 1 Coats et a1.

1451 Oct. 23, 1973 APPARATUS FOR DRAWING FILAMENTS Inventor's: Robert Reid Coats; John Michael Greenway, both of l-larrogate,

England Imperial Chemical Industries A Limited, London, England Filed: Sept. 3, 1971 Appl. No.2 177,695

Assignee:

Foreign Application Priority Data Sept. 3, 1970 0.8. CI. 28/71.3 Int. Cl. D02j 1/22 Field of Search 28/713, 71.4;

References Cited UNITED STATES PATENTS 11/1948 Hitt 28/713 X Mame Great Britain 42,223 70 3,159,964 12/1964 Kretsch 23 713 x 3,471,608 10/1969 Schippers.... 3,623,311 11/1971 Berger 28/713 x Primary Examinerl ,ouis K. Rimrodt Att0mey-Cushman, Darby & Cushman [57] ABSTRACT Apparatus for continuously drawing a filament comprising a filament advancing roll adapted for rotation under the speed controlling influence of a motor and a plurality of other rolls each adapted for rotation under the speed controlling influence of surface contact with the advancing filament before it reaches the advancing roll at least two of such plurality of rolls being coupled for rotation at a predetermined surface speed ratio corresponding to a required draw ratio.

6 Claims, 7 Drawing Figures PATENTED OUT 23 I975 3.766314 $HEET 10F 3 7663114 SHEET 3 BF 3 PATENTEDUET 23 I975 1 APPARATUS FOR DRAWING FILAMENTS This invention relates to apparatus for continuously drawing or relaxing filaments, particularly butnot exclusively melt spunsynthetic'polymer filaments, and

especially to apparatus for drawing or'relaxinga number of similar filament yarnsseparately and simultaneously. By drawing or relaxingwe mean imposing permanent changes of filament length of the *kindthat can be made to occur under positive tension. For brevity in what followssuch changes will be referred to as drawing, and this word is intended to cover all single or multiple stagepositive or negative length changes so long as the tension is positive. V

Apparatus isknown for drawing a continuously advan cingfilament between rolls which are motor driven at different controlled speeds. It is known -to construct multiposition machines with long rotors, each rotor having along its length a number of spacedrollsections so that a number of filaments orbundles of filaments may be advanced separatelyand simultaneously one on each roll section. To preventslip, idler rolls have been provided'whereby' alplurality of short arcs of contact may be created 'betweenfilament and roll. An advantage of long rotors is the relative simplicity ofthe prime movers'and gear boxes provided to drive them. In general, however,-separate rolls,-with free front faces and bearings at the rear, have'been favoured for drawing synthetic filaments, probably because of the greater easeof threading and providing large and multiple arcs of contact betweenfilament and roll. A disadvantage of separate rolls hasbeen that eithercomplex gearbox and transmission systems or multiple slave motor systems have been needed to drive them in groups at equal speeds. It is known to-simplify such drive requirements by mounting pairs of feed and draw rolls coaxially as single driven rotors. i

We have invented a simpler and cheaper method of constructing apparatus for drawing filaments which is particularly economic for multiposition machines.

According to this invention we provide apparatus'for continuously-drawing a' filament, comprising'a filament advancing roll adapted for rotation under the speed controlling influence, of a motor, andla plurality of other rolls, each adapted for rotation underthe speed controlling influence of surface contact with the advancing filament before it reaches the advancing roll, at least two of suchplurality of rolls being coupled for rotation at a predetermined surface speed ratio corresponding to -a required vdraw ratio. In operation such coupled rolls perform the functions of feedand draw rolls and may be associated with any known drawing means such as heaters or snubbing means. When more than one pair of rolls is coupled, the apparatus may provide for multistage drawing.

Especially for use with single filaments or fine denier yarns, we prefer apparatus in which the coupled rolls are sections ofastepped rotor so thatthe surface speed ratio of therollsections-are determinedby theirdi'ameter ratios. Forsimple single stage drawing such a rotor maycomprise asimple-single'stepped combination of a feed roll section and-a =draw roll section and may be formed integrally or have interchangeable parts to provide different draw ratios. Pairs of simple rolls and stepped rotors are preferablyarranged with slightly relatively skewed axes of rotation to provide for spaced multiple arcs of contact between .a filament and the rolls.

The filament tension necessarily created after the higher than tensions which might be selected at this position in conventional drawing machinery. As can easily be shown, this tension is given by the following equation:

where T haul off tension between draw roll and advancing roll T draw tension between feed and draw rolls T feed tensionbefore feed roll R draw ratio I X is a term dependent on the work done against rotor bearing friction Y is a term dependent on rotor windage.

When R is significantly greater than unity, for instance in the common range around 3m 4, we find that X and Y are in practice small, and that T can be much less than T,,

The relative magnitude of these terms may be illustrated by reference to the drawing of 167 decitex 30 filament polyethylene terephthalate yarn at a draw tension of about 1 10 grams. The haul off tension was about 88 grams of which only about 2.5 grams was due tofriction and windage. Variability in this small tension component between positions in a multiposition machine may clearly be held to a small proportion of the draw tension.

Apparatus according to this invention is therefore suited for use in multiposition machines for drawing a plurality of similar filament yarns separately and simultaneously, since the absence of positive roll drives does not introduce unacceptable variability between positions. Apparatus according to the invention also has the outstanding advantages in such applications of being much simpler, lighter, and morecompact than conventional apparatus for the same purpose, since only the advancing rolls need to be driven by an external power source and these may even be a necessary part of a package winding means. Furthermore since the feed and drawrolls need no external driving means, they may be mounted on bearings withinheated enclosures, with consequent minimisation of heat losses.

Apparatus according to this invention is also particularly suitable for use in association with filament supply means which do not .deliver a filament at predetermined speed. For example a filament may be withdrawn from a bobbin or other package by the advancing roll and no driven feed roll is needed. Drawing apparatus according to this invention is therefore particularly suitable for association with filament extrusion apparatus to provide for integrated spin-draw. In such an association no external driving means are needed for any machine element between the extrusion pump and the package winding mechanism.

One preferred form of apparatus according to this invention comprises a pair of single stepped rotors each with a feed roll and a draw roll section, having equal feed and draw roll section diameter ratios, and having relatively skewed axes of rotation. We prefer to provide on such stepped rotors a ridge at each step between roll diameter to prevent advancing filaments from falling from draw to feed roll sections.

closely spaced for self threadability according to our copending application 13357/70, with grooves of different diameters to provide for length changes as required, and mounted in a heated enclosure.

In alternative forms of apparatus according to this invention, rolls may be coupled for rotation at predetermined speed ratios by gears, toothed belts or similar known means. These alternative forms may be preferable for use with heavy tows of filaments.

For the better understanding of the invention, four embodiments will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a front view of a drawing apparatus according to the invention.

FIG. 2 is a side view of the apparatus of FIG. 1.

FIG. 3 is a side view of an alternative drawing apparatus according to the invention.

FIG. 4 is a front view of an apparatus for drawing and relaxing according to the invention.

FIG. 5 is a side view of a multistage drawing apparatus according to the invention with its cover partly cut away.

FIG. 6 is a section on the line VI of FIG. 5, and

FIG. 7 is a section on the line VII of FIG. 5.

Referring to FIGS. 1 and 2, a continuous filament 1 passes from a supply means not shown to an advancing roll 2 driven by means not shown against which it is held in contact without slip by a nip roll 3 held under pressure against roll 2 by conventional means not shown. An idler roll spaced apart from and skewed with respect to the advancing roll 2 may be used instead of the nip roll 3.

Two rolls 4 and 5 are mounted for free rotation but coupled by gears 6 and 7. Two further rolls 8 and 9 are mounted for free rotation with axes slightly skewed with respect to the axes of rolls 4 and 5 respectively. A steam heated enclosure 10 is provided between rolls 8 and 9.

In operation a filament issuing from the supply means is passed through the nip between rolls 2 and 3, passed a number of times round the pair of rolls 5 and 9, entered through the heated enclosure 10, and then passed a number of times round the pair of rolls 4 and 8. The filament, advancing under the influence of roll 2 causes rolls 4, 5, 8 and 9 to rotate and is thereby caused to draw in the heated enclosure to a ratio dictated by the gear ratio between gears 6 and 7.

Referring to FIG. 3 a pair of relatively skewed rotors l1 and 12 have feed roll sections 111 and 121 and draw roll sections 112' and 122. The ratios of the diameters of sections 112 and 122 to 111 and 121 are equal. A heated enclosure 13 is provided between rotors l1 and 12 and there is also an advancing roll 14 and nip roll 15 similar to rolls 2 and 3 of FIG. 1.

In operation a filament 16 issuing from supply means not shown is entered into the nip rolls 14 and 15, passed a number of times round rolls 112 and 122, entered through the enclosure 13 and passed a number of times round rolls 111 and 121. The apparatus then functions as that of FIG. 1.

FIG. 4 illustrates apparatus for drawing and relaxing. A first rotor 20 comprises a feed roll section 201 and a draw roll section 202. A second rotor 21 comprises a draw rollsection 2l1'and a relax roll section 212.

A separate feed roll 22 and relax roll 23 are provided adjacent rotors 20 and 21 respectively and a forwarding roll and nip roll 24 and 25 similar to rolls 2 and 3 of FIG. 1 are provided adjacent roll 23.

The operation is similar to that of the apparatus of FIG. 3. Heated enclosures may be provided for drawing and relaxing or the rolls may be heated or mounted within a heated enclosure.

A triple stepped rotor development of the apparatus of FIG. 3 will provide for two stage drawing.

FIGS. 5, 6 and 7 illustrate a multistage drawing apparatus. A closely spaced pair of self threadable parallel grooved rotors 31 and 32 according to our copending application 13357/ have varying groove depths to provide feed roll sections 311 and 321 at the back end of the rotors, intermediate roll sections 312 and 322, and draw roll sections 313 and 323 at the nose of the rotors.

The rotors are freely rotatable in bearings 33 and 34, mounted in an enclosure 35 with a door 36 string up slots 37 and 38 and heated by means not shown. The apparatus comprises also a motor driven advancing roll system not shown which is similar to rolls 2 and 3 of FIG. 1.

In operation a filament 39A issuing in the direction of the arrow from supply means not shown to advancing means not shown is engaged in the back groove of rotor 32 and then threaded on multiple figure of eight loops round the noses of the rotors. The advancing filament then migrates back along the rotors and threads itself into adjacent grooves.

What we claim is:

1. Apparatus for continuously drawing a filament comprising a filament advancing roll adapted for rotation under the speed controlling influence of a motor and a plurality of other rolls each adapted for rotation under the speed controlling influence of surface contact with the advancing filament before it reaches the advancing roll, at least two of such plurality of rolls being coupled for rotation at a predetermined surface speed ratio corresponding to a required draw ratio.

2. Apparatus according to claim 1 wherein at least one of said other rolls is a rotor with roll sections of different diameters.

3. Apparatus according to claim 2 comprising a pair of similar rotors having relatively skewed axes of rotation.

4. Apparatus according to claim 2 comprising a pair of grooved rolls closely spaced for self threadability and with grooves of different diameters to provide for drawing.

5. Apparatus according to either of claim 4 in which the rotors are in a heatable enclosure.

6. Apparatus according to claim 3 in which the rotors are in a heatable enclosure. 

1. Apparatus for continuously drawing a filament comprising a filament advancing roll adapted for rotation under the speed controlling influence of a motor and a plurality of other rolls each adapted for rotation under the speed controlling influence of surface contact with the advancing filament before it reaches the advancing roll, at least two of such plurality of rolls being coupled for rotation at a predetermined surface speed ratio corresponding to a required draw ratio.
 2. Apparatus according to claim 1 wherein at least one of said other rolls is a rotor with roll sections of different diameters.
 3. Apparatus according to claim 2 comprising a pair of similar rotors having relatively skewed axes of rotation.
 4. Apparatus according to claim 2 comprising a pair of grooved rolls closely spaced for self threadability and with grooves of different diameters to provide for drawing.
 5. Apparatus according to either of claim 4 in which the rotors are in a heatable enclosure.
 6. Apparatus according to claim 3 in which the rotors are in a heatable enclosure. 